Worts of Wisdom Yeast Experiment

Jeremy Bergsman

March-May 1999

Introduction:

In recent years there has been a proliferation in the number of yeast strains available to homebrewers. How does one make an educated choice about which one to use? Are they really different? (See Fix' Analysis of Brewing Techniques.)

WoW has attempted to address this question by producing 21 beers made from identical wort, fermented in identical containers at the same time, from a wide variety of ale yeasts. The wort used was Tied House amber (graciously donated by the Tied House), which is an excellent choice for this experiment--sufficient character to be in line with beers one might realistically want to produce without being overtly hoppy or dominated by any unusual malt characteristics. The yeasts used were all the Wyeast ale yeasts (except the Belgian and Weizen strains), White Labs' Burton and American Wheat (Zum Uerige/Widmer) strains, Head Start's Alt yeast, and WoW's own top secret, fast acting, high temperature-tolerant strain. Yeast was kindly donated by Wyeast and Fermentation Frenzy.

Procedure:

Yeast Culturing:

Wyeast XL packs (175 mL) dated 3/24/99 pitched into 350 mL sterile wort on 3/28/99. Some packages (the more flocculant ones) didn't release all their yeast (should have shaken well).
White Labs dated 3/15/99 pitched into 350 mL sterile wort on 3/28/99.
50 mL culture WoW ale yeast pitched into 450 mL sterile wort (LME + DAP, SG ~1.040) on 3/28/99.
50 mL culture Head Start Alt yeast pitched into 450 mL sterile wort on 3/29/99.

Fermentation:

Pitch March 30 into ~2.5 gallons Tied House Amber wort, saturated with O₂ at ~10 PSI. Fermentation in 5 gallon soda kegs at ambient temperature (58-62 degrees F) and pressure (safety release valves left open).

Starting on 4/7/99 fermentation was monitored by closing the safety valve for 1 hour. If the pressure built up during this time escaped in less than 2 seconds, the keg was then tested for 24 hours. If the pressure from this longer test escaped in less than 2 seconds the kegs was closed for good. Two batches were closed on the first test. The rest were finished within a week or so. Since pitching rates were not measured and were probably not similar, we don't report the finishing time for each yeast. There was no racking at any point--beer was served from the primary fermenter.

Serving:

Kegs were saturated with CO₂ at 25 PSI with shaking 3 days before serving, which took place on May 2. Kegs remained at ambient temperature and beer was served through a jockey box. Dispensing was satisfactory for most beers, and comments about carbonation have been ignored here. The first few ounces from each keg was cloudy, but most cleared well after this. Comments about cloudiness in some beers have also been omitted from these results. Food was available throughout the tasting, which took place over several hours on one day.

Tasting Results:

Tasters received a form with categories as shown below. They were allowed to give feedback in any way they liked and were not required to turn in their tasting form. Tasters used various forms of quantitative feedback (e.g. numeric, "low, medium, high"), which were converted to 1-10 scale. I attempted to be consistent within each person's scale, but numbers may not be consistent across people. Tasting was not blind.

The complete transcribed tasting data are available as a 60KB Microsoft Excel 7/PC file here. Following is a summary of the responses:

Numeric data are averages of quantitative responses, where given.
Most people did not taste all the beers. Most beers were tasted by at least 6 people, some include as many as 15 responses.
Over 1000 comments are represented by the following table.
Some comments were shifted by me to what seemed a more appropriate column.
The following summary table makes note of comments given more than once. "Often" signifies more than 3-4 times depending on number of responses. No entry signifies few, inconsistent responses.

Yeast Name	Wyeast # (Unless otherwise noted)	Malt Quality	Malt Quantity	Sweetness	Ester Quality	Ester Quantity	Other Fermentation Character (solvent, phenol...)	Bitterness	Other hop comments	Other comments
Ale yeast blend	1087	4, thin	4	3	various fruits noted	5	a few off characters	3		thin, yeasty
American	1056	4, neutral	4	4	good, some fruits noted	3	a few off characters, including phenol	4		clean/neutral often noted, but a few off notes too
American II	1272	5, caramel	5	4	banana, other fruits noted	3	a few off characters, including phenol	4
American Wheat	1010	3	4	5	various fruits noted	4	phenol and sulfur often noted, other off notes too	4		wheat beer taste
British	1098	4	4	4	various fruits noted	4	diacetyl often noted	3		acidic
British II	1335	5	4	4	clean, some fruit noted	3	a few off characters	4	More aroma than most	clean/neutral often noted
Burton Ale	White Labs WLP023	4, neutral	4	4		4	a few off characters, including phenol/spice and sulfur	4	lower aroma than most	various negative comments
East Coast Ale	White Labs WLP008	3	4	3	3	5		6	4	clean/neutral, negative comments
European	1338	5	5	4	7	4		3
German	1007	7	7	6	1	6		5		fart/fecal
Head Start Alt			4	3	2	4	sulfur often noted (5/7)	4	3	sour, infected? (one person each)
Irish	1084	5	4	5		4		4
London	1028	6, some positive comments	5	4	5	4	diacetyl, clean	4		positive comments
London III	1318	5	5	5	5	4	a few off characters	4	More hop flavor/aroma than most	positive comments, [astringent/chalky (one person each)]
London ESB (II)	1968	6	5	5	5, melon and other fruits noted	4	clean, also a few off characters	4	a bit more than most	citrus
Northwest	1332	5	4	4	5	6		5		positive comments
Ringwood	1187	6	5	5	5	4		4
Scottish	1728	5	5	5	5	5	a few off characters	4	lower than most	citrus
Thames valley	1275	6	5	4	6	4	a few off characters	6		positive comments
Whitbread	1099	5	5	4	3	4	diacetyl, veggie	3
WoW		6	4	5	8	5		4		positive comments

The general consensus was that fermentation temperature was too low for the yeast to exhibit their best performance. With the exception of a few yeasts, any esters noted here were very subdued and in any other context these beers would have been called very clean. Likewise, I feel that the occaisional mention of phenol should not be taken to indicate contamination since in every case a minority of people detected anything in this area. All comments are those of people desperately trying to find something unusual in one of a series of very plain, very similar beers.

Credits:

Peter and Carol Torgrimson assisted with the wort pick up and provided the fermentation space and monitoring. Jeff Schroeder assisted with keg cleaning and hosted the tasting. The Worts of Wisdom paid for the materials that were not donated. Various members of WoW and other local clubs lent kegs. Yeast was donated by Fermentation Frenzy and Wyeast, and the wort was donated by the Tied House. Lee Shephard offered advice on the tasting.